Information recording medium, apparatus and method for recording or reproducing data thereof

ABSTRACT

An information recording medium suitable for optical discs such as DVD-RAM is provided for integrated management of data as objects in different kinds of AV formats. Also apparatus is provided for data recording and playing to the medium. The medium stores management information including program chain information (PGC information) defining the playback order of the objects, and object information containing information relevant to the objects. The object information has general information of the object, attribute information and a map associating a playback time point of the object with an address on the optical disc of a component of the object to be played. The PGC information has cell information including information about type of object, identification information. The order of the cell information in the PGC information corresponds to the order in which the objects are played back.

This is a Rule 1.53(b) Divisional Application of Ser. No. 09/414,958,filed Oct. 12, 1999.

This application is based on application No. 10-289089 filed in Japan,the contents of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to readable/writable information recordingmedium. More specifically, the present invention relates to aninformation recording medium for recording multimedia data in differentkinds of formats such as movie image data, still picture data and audiodata; and a data recording apparatus and replaying apparatus for themedium.

2. Related Art

Development of phase change type disc DVD-RAM has increased recordingcapacity of a rewritable optical disc from about 650 MB to a few GB. TheDVD-RAM is now expected to become a medium not only for computers butalso a recording/playing medium for audio/video (hereinafter abbreviatedas AV) technologies in combination with standardization of a digital AVdata coding technique called MPEG (MPEG2). Specifically, the DVD-RAM isexpected to replace magnetic tape which has been a major AV recordingmedium.

(DVD-RAM)

Advancement in high-density recording technology for rewritable opticaldiscs in recent years has made it possible to store not only computerdata and audio data but also image data as well.

Conventionally, lands and grooves are formed on a signal recordingsurface of the optical disc.

Signals used to be recorded only on the land portion or in the grooveportion. Later, land-group recording method was developed for recordingsignals both in the land portion and in the groove portion, practicallydoubling the recording density. For example, a technique disclosed inJapanese Patent Laid-Open Publication No. 8-7282 is well known.

Another of such techniques is CLV (Constant Linear Velocity recording)method for improving recording density. From this technique, zone CLVmethod was developed and is now commercially practiced for simplifiedcontrol in application. Japanese Patent Laid-Open Publication No.7-93873 is a known example of this technique.

With such development in the optical disc for greater recordingcapacity, a technological challenge is how to record AV data includingimage data, thereby achieving new performances and functions that havenever been realized by prior art AV apparatuses.

The development of the large-capacity rewritable optical disc isexpected to replace the conventional tape medium for recording/playingAV data. The change from tape to disc will bring substantial changes inthe function and performance of the AV equipment.

The biggest change to be brought by the disc is tremendous improvementin random access capability. If tape is to be accessed randomly,rewinding time of the tape, which is usually a few minutes per reel,must be taken into account. Such an access time is extremely slower thana seek time (which is shorter than a few tens of millisecond.) for theoptical disc. Thus, in a practical sense, the tape cannot be a randomaccess medium.

Such a superb random access capability of the optical disc can realizedistributed recording of AV data in the optical disc, which was notpossible with the conventional tape medium.

Referring now to the attached drawings, FIG. 1 is a block diagram of aDVD recorder drive unit. The drive unit comprises an optical pickup 11for reading data stored in a DVD-RAM disc 100, an ECC (Error CorrectingCode) processor 12, a one-track buffer 13, a switch 14 for selectingbetween input and output to and from the track buffer 13, an encoder 15,and a decoder 16.

As shown in the figure, the DVD-RAM disc 100 uses one sector (1 sector=2KB) as a smallest unit of data recording, and one ECC block (1 ECCblock=16 sectors) is used as a unit for error correcting operationperformed by the ECC processor 12.

The track buffer 13 is a buffer for storing AV data at a variable bitrate to record AV data effectively in the DVD-RAM disc 100.Specifically, reading/writing for the DVD-RAM 100 is performed at afixed rate (Va), whereas the bit rate (Vb) of AV data is variedaccording to complexity of contents (e.g. an image for video data). Thebuffer 13 absorbs difference between these two bit rates. When the AVdata have a fixed bit rate such as in a video CD, then the track buffer13 is not required.

If this track buffer 13 is used more effectively, distributed recordingof AV data on the disc 100 becomes possible. This will be described morespecifically here below, referring to FIGS. 2A and 2B.

FIG. 2A is a diagram showing address space on the disc. According toFIG. 2A, AV data is stored in a distributed manner, i.e. in a continuousarea [a1, a2] and in another continuous area [a3, a4]. In such a case,the AV data can be replayed continuously supplying data stored in thebuffer 13 to the decoder portion 16 while seek is being made from pointa2 to point a3. This situation is shown in FIG. 2B.

The AV data starting from the location al are read, and then entered tothe track buffer 13 from time t1, upon which time the track buffer 13begins to output the data. Thus, the buffer 13 accumulates data at arate equal to the difference (Va−Vb) between the input rate (Va) to thebuffer 13 and the output rate (Vb) from the buffer 13. This situationcontinues until the retrieval reaches a2 represented by a time point t2,by which time the amount of data in the buffer 13 has accumulated toamount B(t2). From time t2 to time t3, until the data pickup operationis resumed from the area starting at a3, the amount of data B(t2) storedin the track buffer 13 is being consumed in order to keep the decoder 16supplied with data.

In other words, when the amount of data ([a1, a2]) read before theseeking is greater than a certain volume, then the AV data can becontinuously supplied without being interrupted by the seek.

The above description is for reading of data from the DVD-RAM, i.e. fora play back operation. The same goes with writing data to the DVD-RAM,i.e. for a recording operation.

As described above, with the DVD-RAM, continuous replaying/recording ispossible even if AV data is stored in the distributed manner, as long asthe amount of data on each continuous record is greater than a certainvolume.

In order to enhance advantages of the large-capacity recording medium,i.e. DVD-RAM, a UDF (Universal Disc Format) file system is used in theDVD-RAM as shown in FIG. 3 to allow access to the disc by using a PC.UDF information is recorded in “Volume” area of the diagram. Details ofthe UDF file system is disclosed in the “Universal Disc FormatStandard.”

(Prior-art AV equipment)

Next, description will be made for prior art AV equipment commonly usedby many users.

FIG. 4 is a diagram showing relationships among conventional AVequipment, media and formats. For example, if a user wants to watch avideo program, a videocassette must be loaded into a VTR, and theprogram must be viewed using a TV set. If the user wants to listen tomusic, then a CD must be loaded into a CD player or CD radio-cassetteplayer, and the program must be listened through a speaker system orthrough headphones. Specifically, according to the conventional AVsystem, each format (video or audio) is paired with a correspondingmedium, respectively.

For this reason, each time when listening or watching a program, theuser must select an appropriate medium and change one to another AVequipment appropriate to the medium. This is inconvenient from theuser's viewpoint.

(Digitization)

Meanwhile, along with recent popularization of digital technology, a DVDvideodisc was introduced as package software, whereas satellite digitalbroadcast was introduced in the broadcasting industry. Thesedevelopments are backed by digital technology innovation, especially byMPEG as an internationally accepted standard.

FIG. 5 is a diagram showing MPEG streams used in the DVD videodisc andthe satellite digital broadcast mentioned above. The MPEG standard has ahierarchy structure as shown in FIG. 5. An important point to note hereis that the MPEG stream eventually used by an application in the packagemedium such as the DVD videodisc is different from the MPEG stream inthe communication medium such as the satellite digital broadcasting. Theformer is called “MPEG program stream”, in which data transfer is madeby the unit of pack, reflecting the size of a sector (2048 bytes in DVDvideo disc) as the unit of recording in the package software. On theother hand, the latter is called “MPEG transport stream”, in which theunit of data transfer is a TS packet having a size of 188 bytes,reflecting the application to ATM (Asynchronous Transfer Mode) systems.

The MPEG is expected to eliminate borders between different AV media, asa universal coding technology of image signals and digital data.However, because of such small differences as described above, there isnot yet any AV equipment or media capable of handling both the packagemedia and communication media.

(Changes Brought by DVD-RAM)

Introduction of the large capacity DVD-RAM is a step forward toelimination of the inconvenience that users feel in conventional AVequipment. As described earlier, the DVD-RAM incorporated with the UFDfile system is accessible from the PC. By using different pieces ofapplication software on the PC, it is now possible to play varieties ofcontents such as video, still picture and audio programs on a singlepiece of equipment, i.e. the PC.

As shown in FIG. 6, the user can move a cursor with a mouse onto a filedisplayed on a screen, and then double-click (or single-click) to replaycontents of the file such as a movie displayed in left-top area of thescreen.

Such a convenience becomes possible by combination of flexibilityoffered by the PC and large storage capacity offered by the DVD-RAM.

Backed by increasing popularity of the PC in recent years a number ofdifferent AV data can now be handled fairly simply on the PC as shown inFIG. 6. However, even though number of PC users is expected to increase,the popularity and easiness of operation of the PC are not so high andsimple as those of the home TV or home video systems.

It is therefore an object of the present invention to solve thefollowing problems identified as hurdles to optimum performance of theoptical discs such as the DVD-RAM, as an AV recording medium of the nextgeneration.

A world to be realized by the DVD recorder would be a world in which theuser can freely handle different formats and contents without caringabout the differences, by using a single medium on a single piece of AVequipment as shown in FIG. 7.

FIG. 8 shows an example of a menu used in the DVD recorder. According tothis menu, the user can select from 1) “The Foreign Movie Theater”recorded from satellite digital broadcasting, 2) “The Morning DramaSeries”, 3) “The World Cup Finals” each recorded from conventionalterrestrial broadcasting, and 4) a Beethoven dubbed from a CD, on a TVscreen without caring about the original medium or the recording format.

The biggest problem in developing such a DVD recorder as above is how tomanage uniformly the AV data and streams of many different formats.

No special managing method will be necessary if only a limited number ofexisting formats are to be handled. However, a managing method capableof handling not only a number of existing formats but also new formatsto be introduced in the future has to be developed in order to realizethe above-mentioned world of DVD recorder.

Even so, certain difference between a future user interface and thoseincorporated in the capability of uniformly handling the different AVstreams may create a certain level of inconvenience similar to theinconvenience described for the prior-art. Specifically, the user mayhave to perform different operation depending upon the contents orformat.

SUMMARY OF THE INVENTION

The present invention is made to solve the above problem, and it istherefore an object of the present invention to provide an informationrecording medium capable of uniformly handling different kinds of AVstreams, and to provide a recording apparatus and a playing apparatusfor said information recording medium.

In a first aspect of the invention, an information recording medium isprovided for recording objects which include at least one of image dataand audio data. The recording medium stores object information andplayback control information.

The object information includes identification information and mapinformation for each object. The identification information identifiesthe object. The map information associates a playback time of the objectwith a logical address (or address on a disc) of a component of theobject on the medium. The component is played back at the playback time.

The playback control information includes at least one of cellinformation in a predetermined order. The cell information contains typeinformation, identification information and playback sectioninformation. The type information indicates a kind of the object. Theidentification information identifies the object. The playback sectioninformation specifies a section in which the object is being played.

The order of cell information in the playback control informationindicates the order in which the objects specified by respective cellinformation are played.

In a second aspect of the invention, an apparatus for recording data tothe information recording medium comprises a unit for receiving an MPEGtransport stream from external equipment, a unit for reading the“random_access_indicator” from the received MPEG transport stream and aunit for generating an access point information based on the read“random_access_indicator”.

In a third aspect of the invention, an apparatus for recording data tothe information recording medium comprises a unit for recording typeinformation and the type information indicating a kind of object to theplayback section information.

In a fourth aspect of the invention, an apparatus for reading data fromthe information recording medium comprises a pickup unit for readingdata of the object recorded in the recording medium, a plurality ofdecoding units for decoding the data of the object according to the kindof the object, a selecting unit for selecting one of the decoding unitsfor playback operation and a controlling unit for reading the typeinformation of the object specified in the object information, andcontrolling the selecting units to select one of the decoding unitsaccording to the read type information.

In a fifth aspect of the invention, a method for recording data to theinformation recording medium comprises the steps of receiving an MPEGtransport stream from external equipment, reading the“random_access_indicator” from the received MPEG transport stream andgenerating an access point information based on the read“random_access_indicator”.

In a sixth aspect of the invention, a method for reproducing data fromthe information recording medium, comprises the steps of reading outobject data from the recording medium, reading out the type informationof the playback control information in the recording medium, anddecoding the read object data according to the read type information.

The recording medium according to the present invention makes possiblenot only to record but also to integrally manage different AV formats onthe same disc, thereby making possible to manage a variety of objectseach recorded in a different format on one recording medium.

The apparatus and method for recording according to the presentinvention makes possible to create and record the type information forindicating the kind of objects to be recorded, thereby making possibleto embody the above optical disc compatible to the variety of AVformats.

The apparatus and method for reproducing according to the presentinvention makes possible to decode data of read object in the externalequipment even if the playing apparatus does not have the capability todecode the data of the read object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a drive unit of a DVD recorder.

FIG. 2A is a diagram showing address space on a disc.

FIG. 2B is a diagram showing data accumulation in a track buffer.

FIG. 3 is a diagram showing a file structure through a file system.

FIG. 4 is a diagram showing relationships among different kinds of priorart AV equipment and corresponding media.

FIG. 5 is a diagram showing an MPEG program stream and an MPEG transportstream.

FIG. 6 is an illustration of a PC screen when an AV data file is beingaccessed on the PC.

FIG. 7 is a diagram showing relationships to be created by a DVDrecorder among different kinds of AV equipment.

FIG. 8 is an example of a selection menu given by the DVD recorder.

FIG. 9A is a diagram showing relationships between an AV file and adirectory on the computer readable DVD-RAM disc.

FIG. 9B is a diagram showing address space on the disc.

FIG. 10 is a diagram showing relationships among an object, objectinformation and PGC information.

FIG. 11 is a diagram showing management information derived from theobject information for each stream.

FIG. 12 is a diagram showing relationships among a movie object (M_VOB),movie object information (M_VOBI), and PGC information (PGCI).

FIGS. 13A, 13B, 13C, 13D, 13E and 13F are diagrams describing a time mapaccording to the present invention.

FIGS. 14A, 14B, 14C and 14D are diagrams each of which shows each stageof the MPEG transport stream.

FIG. 15 is a diagram showing relationships between an audio object(AOB), audio object information (AOBI) and PGC information (PGCI).

FIG. 16 is a diagram showing relationships among a still picture object(S_VOBS), still picture object information (S_VOBS), and PGC information(PGCI).

FIG. 17 is a diagram describing management information in a DVD-RAM.

FIG. 18 is a block diagram of a player model according to the presentinvention.

FIG. 19 is a block diagram of the DVD recorder according to the presentinvention.

FIG. 20 is a Block diagram of a DVD player or a data reproducingapparatus according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the accompanying drawings, detailed description willbe made for a DVD-RAM, a DVD recorder, and a DVD player as preferredembodiments of the present invention.

(Logic Structure of Data on DVD-RAM)

The DVD-RAM according to the present invention makes possible to recordand manage integrally AV data and AV streams of many different kinds offormats on a single disc. This allows it to record on a single disc AVstreams of different formats including a terrestrial broadcasting TVprogram, a digital broadcasting TV program transmitted in the MPEGtransport stream format, a video stream taken by a digital video camera,a still picture taken by a digital still camera, and video data coded inthe MPEG program stream, and so on. Further, the data recorded in theDVD-RAM can be played in a given sequence. For this purpose, the DVD-RAMaccording to the present invention is provided with managementinformation for managing the AV streams without depending on the typesof format of the AV data or AV streams.

First, structure of the data recorded in the DVD-RAM according to thepresent invention is described with reference to FIGS. 9A and 9B. Adiagram in FIG. 9A is a data structure of a DVD-RAM disc 100, which canbe seen by a file system. FIG. 9B shows a structure of a physical sectorin the disc 100.

As shown in the figure, a first portion of the physical sector is alead-in area 31 which stores therein standard signals necessary forstabilizing servo mechanism, identification signals for differentiatingfrom other media, and so on. The lead-in area 31 is followed by a dataarea 33 which stores logically available data. A last portion is alead-out area 35 storing signals similar to those in the lead-in area31.

A front portion of the data area 33 stores volume information which ismanagement information for the file system. Since the file system is aknown technique, no details will be described herein.

The file system allows the data in the disc 100 to be handled asdirectories and files as shown in FIG. 9A. As understood from FIG. 9A,all the data handled by the DVD recorder is managed under VIDEO_RTdirectory immediately below the ROOT directory.

The DVD recorder according to the present embodiment handles two kindsof files, i.e. AV files containing audio-video data (AV data), andmanagement information files containing information for managing the AVfiles. According to the example shown in FIG. 9A, the managementinformation file is identified as “VIDEO_RT. IFO”, whereas the AV filesinclude a file “M_VOB.VOB” which contains movie data, “D_VOB.VOB” whichcontains image data from digital broadcasting, “AOB. AOB” which containsaudio data, and so on. Each of these files will be detailed here below.

It should be noted here that according to the present embodiment, eachAV stream is defined as an object (“Object”). Specifically, the objectsmay include a variety of AV streams such as MPEG program stream, MPEGtransport stream, audio stream, still picture data, and so on. Each ofthese AV streams is abstracted as the object so that the managementinformation of these AV streams can be defined as object information(Object I) of a universal format.

(Management Information)

First, the management information will be described referring to FIG.10. The management information has object information 80 for managementof recording locations of the object and attribute thereof, and programchain information (PGC information) 50 and 70 which define playbacksequence, playback time and so on for data to be played back from theDVD-RAM.

The above-described abstraction is possible for the AV streams becausethe AV streams have time attribute and other elements in common,although each of the different formats has certain differences from theothers. AV streams having a common format are stored in a same AV filein the order of recording.

The object information (Object I) 80 includes general information aboutthe object (Object GI) 80 a, attribute information of the object(Attribute I) 80 b, and an access map 80 c for converting the objectplayback time into addresses on the disc.

The access map 80 c is necessary because the AV stream generally has twostandards, i.e. a time domain and a data (binary digit string) domain,which do not have perfect correlation with each other. For example, in avideo stream coded by MPEG-2 video which is now an internationalstandard of the video stream, use of variable bit rate (a method inwhich the bit rate is changed depending on the level of complexity of animage) is becoming a mainstream. According to this method, there is noproportional relationship between the amount of data from the beginningand the accumulated length of playback time, and therefore randomaccessing cannot be performed based on the time axis. In order to solvethis problem, the object information 80 has the access map 80 c forconversion between the time axis and the data (binary digit string)axis. As will be described later, one object comprises a plurality ofobject units (VOBU), and therefore the access map 80 c has data thatcorrelates or associates the time region with the address region foreach of the object units.

The PGC information 50, 70 are the information for controlling theplayback of the object, i.e. image data and audio data. The PGCinformation 50, 70 represent a unit of data to be played back when theDVD player plays continuously data back. Specifically, each of the PGCinformation 50, 70 indicates an object to be replayed, and a playbacksequence of cells 60, 61, 62 and 63. Each of cells 60, 61, 62 and 63indicates any playback section of this particular object. The cells 60,61 . . . will be described later in more detail. The PGC informationcomprises two kinds of information comprising an original PGCinformation 50 and a user defined PGC information 70. The original PGCinformation 50 is automatically generated by the DVD recorder uponrecording the object so that all of the recorded objects are included.On the other hand, with the user-defined PGC information 70, the usercan freely define the playback sequence. The PGC information 50 and 70have the same structure and function differing only in that theuser-defined PGC information 70 is defined by the user. Thus,description in further detail will be made only for the original PGCinformation 50.

As shown in FIG. 10, the original PGC information 50 includes at leaseone of the cell information. The cell information 60 . . . specifies anobject to be replayed, and a replay section of the object. Generally,the PGC information 50 records a plurality of cells in a certainsequence. This recording sequence of the cell information in the PGCinformation 50 indicates the sequence in which the objects specified inrespective cells are replayed.

Each cell, the cell 60 for example, includes type information (“Type”)60 a which indicates the kind of object specified, an objectidentification (Object ID) 60 b which identifies the object, startingposition information (“Start”) 60 c on the time axis of the object, andending position information (“End”) 60 e on the time axis in the object.

When the data is replayed, the cell information 60 in the PGCinformation 50 is read out successively, so that the object specified bythe cell is replayed by successively playing portions of the objectrepresented by the playback sections specified by respective cells.

(Subclasses of the Object Information)

In order for the abstracted object information to be applied to anactual AV stream, a concretization must be provided. This principle maybe understood easily as the class concept employed in an object-orientedmodel. More specifically, understanding will become easier if the objectinformation is considered as a super-class, and more concrete structurescreated for each of the AV streams are considered as subclasses. FIG. 11shows these concretized subclasses.

According to the present embodiment, as shown in FIG. 11, the objectinformation has subclasses defined as a movie subclass, a still picturesubclass, an audio subclass, and a digital broadcast subclass.Specifically, following subclasses are defined as concrete information:Movie object information (M_VOBI) is defined as the object informationfor video data (in MPEG program stream). Digital video objectinformation (D_VOBI) is defined as the object information for digitalbroadcasting (in MPEG transport stream). Audio object information (AOBI)is defined as the object information for audio, and still picture videoobject information (S_VOBI) is defined as the object information forstill pictures. Each of the above will be described here below.

The movie object information 82 includes MPEG program stream generalinformation (M_VOB_GI) 82 a, movie object stream information (M_VOB_STI)82 b, and a T map 82 c.

The general information (M_VOB_GI) 82 a includes movie objectIdentification information (M_VOB_ID), movie object recording time(M_VOB_REC_TM), movie object starting time information (M_VOB_V_S_PTM),and movie object ending time information (M_VOB_V_E PTM).

The movie object stream information (M_VOB_STI) 82 b includes videostream information (V_ATR) having coding attributes of the video stream,the number of audio streams (AST_Ns), and audio stream information(A_ATR) having coding attributes of the audio stream.

The T map 82 c includes a leading address of the movie object in the AVfile, playback time (VOBU_PB_TM) and data size (VOBU_SZ) of each of themovie object units (VOBU). The movie object unit (VOBU) is the smallestunit to be accessed in the movie object (M_VOB), and will be detailedlater.

The digital broadcast object information (D_VOBI) 86 includes MPEGtransport stream general information (D_VOB_GI) 86 a, stream information(D_VOB_STI) 86 b, and a T map 86 c.

The general information of the digital broadcasting object (D_VOB_GI) 86a includes digital broadcasting object identification information(D_VOB_ID), digital broadcasting object recording time (D_VOB_REC_TM),digital broadcasting object starting time information (D_VOB_V_S_PTM),and digital broadcasting object ending time information (D_VOB_V_E PTM).

The digital video object stream information (D_VOB_STI) includesinformation (PROVIDER_INF) which contains additional informationprovided in the digital broadcasting. The T map 86 c includes a leadingaddress of the digital broadcasting object (D_VOB) in the AV file,playback time (VOBU_PB_TM) and data size (VOBU_SZ) for each object unit(VOBU).

The audio object information (AOBI) 88 includes audio stream generalinformation (AOB_GI) 88 a, stream information (AOB_STI) 88 b, and a Tmap 88 c. The audio stream general information (AOB_GI) 88 a includesaudio object identification information (AOB_ID), audio object recordingtime (AOB_REC_TM), audio object starting time information (AOB_S_TM),and audio object ending time information (AOB_E_TM). The AOB streaminformation (AOB_STI) 88 b includes audio stream information (A_ATR)having coding attributes of the audio stream. The T map 88 c includes aleading address of the audio object in the AV file, playback time(AOBU_PB_TM) and data size (AOBU_SZ) for each audio object unit (AOBU).The audio object unit (AOBU) is the smallest access unit in the audioobject (AOB), and will be detailed later.

Still picture object information (S_VOBSI) 84 includes still picturegeneral information (S_VOBS_GI) 84 a, still picture stream information(S_VOBS_STI) 84 b, and an S map 84 c. The still picture generalinformation (S_VOBS_GI) 84 a includes still picture objectidentification information (S_VOBS_ID), still picture object recordingtime (S_VOBS_REC_TM), still picture object starting picture number(SVOBS_S_NO), and still picture object ending picture number(SVOBS_E_NO). The still picture stream information (S_VOBS_STI) 84 bincludes still picture attribute information (V_ATR) having informationabout a compression format of the still picture object. The S map 84 cincludes a leading address of still picture object (S_VOBS) in the AVfile, and data size (S_VOB_SZ) for each still picture.

As described above, a stream information table corresponding to eachtype of AV stream can be defined as shown in FIG. 11 by putting theabstracted object information into a more concrete data.

(Correspondence between Object Information and Cell Information)

Referring next to FIG. 12, the movie object information (M_MOBI), whichis one of the concrete forms of the object information (Object I), istaken as an example to see correspondence with the cell information.

When the type information (Type) specified in the cell information hasthe value “M_VOB”, this cell corresponds to a movie object. Likewise,when the type information has the value “D_VOB”, then the cellcorresponds to a digital broadcasting object, and when the typeinformation has the value “AOB”, then the cell corresponds to an audioobject.

Based on the object ID (Object ID), the object information (VOBI)corresponding to the ID can be found. The object ID has a one-to-onecorrespondence to the movie object ID (M_VOB_ID) contained in thegeneral information (M_VOB_GI) of the movie object information(M_VOB_I).

As described above, the object information corresponding to the cellinformation can be retrieved by using the type information (Type) andthe object ID (Object ID).

The starting position information (Start) in the cell informationcorresponds to the start time information (M_VOB_V_S_PTM) of the movieobject information. When the two values indicate a same time, itindicates that the cell is the first portion to be played of the movieobject. On the other hand, when the starting position information(Start) has a value greater than that of the start time information(M_VOB_V_S_PTM), it indicates that the cell is to be played as a middleportion of the movie object. In such a case, the playback of the cell isdelayed from the top of the object by the difference (time difference)between the start time information (M_VOB_V_S_PTM) and the startingposition information (Start). The same relationship exists between thecell ending position information (End) and the end time information (MVOB_V_E_PTM) of the movie object.

As described above, playback starting and the ending of a given cell canbe obtained as relative points of time within the object by using thestarting information (Start) and the ending information respectively inthe cell information, and the start time information (M_VOB_V_S_PTM) andend time information (M_VOB_V_E_PTM) respectively in the generalinformation (M_VOB_GI) of the movie object information (M_VOBI).

The T map of the movie object is a table comprising a playback time anddata size for each movie object unit (VOBU). By using the T map, therelative playback start time and the relative playback end time of agiven cell within the movie object described above can be converted toaddress data.

Now, the address conversion using the T map mentioned above will bespecifically described with reference to FIGS. 13A, 13B, 13C, 13D, 13Eand 13F.

FIG. 13A shows movie objects (M_VOB) representing video display on thetime axis. FIG. 13B shows the time map comprising the length of playbacktime and the data size for each movie object unit (VOBU). FIG. 13C showsthe movie object expressed on the data (sector series) axis. FIG. 13Dshows pack series as an enlarged portion of the movie object. FIG. 13Eshows a video stream. FIG. 13F shows an audio stream.

The movie object (M_VOB) is an MPEG program stream. In MPEG programstream, a video stream and an audio stream are assembled into a packet(PES packet), and a plurality of the packets (PES packets) are packedinto a sequence. In the example, one pack contains one packet (PESpacket), and a pack is allocated with one sector (=2048 B) for easieraccess. Further, packed video packs (V_PCK) and audio packs (A_PCK) aremultiplexed into a single stream. All of these are illustrated in FIGS.13C, 13D, 13E and 13F.

Further, an MPEG system stream (a general term for the program streamand transport stream) contains time stamps for synchronized playback ofthe multiplexed video and audio streams. The time stamp for the programstream is PTS (Presentation Time Stamp) which indicates the time whenthe frame is to be played. The movie object start time information(M_VOB_V_S_PTM) and the movie object end time information(M_VOB_V_E_PTM) mentioned earlier are time information obtained from thePTS. On the other hand, the time stamp for the transport stream is PCR(Program Clock Reference) which indicates the time of input of data tothe buffer.

The movie object unit (VOBU) is described below. The movie object unit(VOBU) is the smallest access unit within the movie object (M_VOB). Inorder to accomplish highly efficient image compression, the MPEG videostream uses not only image compression using spatial frequencycharacteristics within a video frame but also image compression usingmotion characteristics between the frames, i.e. motion characteristicson the time axis. This means that expansion of a video frame requiresinformation on the time axis, i.e. information about a future videoframe or a past video frame is required, or that the video frame may notbe expanded by itself In order to solve this problem, in MPEG videostream, a video frame (called I-picture) having no motioncharacteristics on the time axis is inserted every about 0.5 second,achieving higher random accessability.

The movie object unit (VOBU) includes some packs from a pack containingthe leading data of an I-picture to a pack immediately before a packcontaining the leading data of the next I-picture. Thus, the T mapcomprises the data size (the number of packs) of each object unit (VOBU)and the playback time (the number of fields) of the video frames withinthe object unit (VOBU).

For example, an assumption is made that the value of Start in the celldiffers from the value of start time information (M_VOB_V_S_PTM) of themovie object by one second (60 fields).

Now, the playback start time of each object unit in the movie object(M_VOB) can be obtained by accumulating the playback time (length) ofeach object unit (VOBU) in the T map from the first movie object.Likewise, the address of each object unit in the movie object (M_VOB)can be obtained by accumulating the data size (the number of packs) ofeach object unit from the first object unit.

According to the present embodiment, the first three object units (VOBU)of the movie object (M_VOB) have 24, 30 and 24 fields respectively.Thus, from the above calculation method, the video frame after onesecond (60 fields) from the top of the movie object (M_VOB) is found tobe included in the third object unit (VOBU#3). Likewise, the startaddress of the third object unit (VOBU#3) is found to be the 223rdsector from the head of the object since these object units (VOBU)respectively have data sizes of 125, 98 and 115 sectors.

Adding the obtained address value to the address value for 5010 sectorswhich is the M_VOB start address (ADD_OFF) within the AV file providesthe start address of the data to be played.

In the above example, assumption is made that the video frame which isthe 60th field from the top of the movie object (M_VOB) is to be played.As mentioned earlier however, the MPEG video does not allow decoding orplayback from any one of all video frames. For this reason, the playbackstarts from the top of the object unit (VOBU) shifted by 6 fields awayfrom the 60th field so that the playback starts from the I-picture. Itshould be noted that a playback can be started exactly from the videofield specified by the cell by decoding the above 6 fields withoutdisplaying.

The method described above can also provide playback end time of themovie object corresponding to the end location in the cell information,and the address of the movie object in the AV file.

Next, the digital broadcasting object information (D_VOBI) will bedescribed. The digital broadcasting object information is basically thesame as the movie object information because the digital broadcastingobject is a subclass derived from the object information. A bigdifference, however, is that the movie object (M_VOB) is created byrecording a terrestrial broadcasting. Specifically, while the movieobject is an AV stream encoded by the recorder itself, the digitalbroadcasting object (D_VOB) is not an AV stream encoded by the recorderitself since in the digital broadcasting object data transmitted from adigital broadcast satellite is recorded directly.

More specifically, when encoding is made by the recorder, internalstructure of the stream is clearly known; however, when the data is aresult of direct recording, internal structure is not known unless thestream is not analyzed, and therefore it is impossible to make the Tmap.

It is possible to analyze the MPEG transport stream supplied through thedigital satellite broadcast. In the present embodiment, the T map iscreated by using information within the MPEG transport stream as to bedescribed here below.

FIG. 14A shows an MPEG transport stream. FIG. 14B shows an enlarged viewof transport packets. FIG. 14C shows PES packets. FIG. 14D shows a videostream.

As shown in FIG. 14A, the MPEG transport stream comprises a series oftransport packets. The transport packet includes a header, an adaptationfield, and a payload. The adaptation field includes a random accessindicator (“random_access_indicator”). The random access indicatorindicates that in this transport packet or the following transportpacket (more precisely, the transport packet having the same programID), a next PES packet (i.e. the PES packet in which the first byte ofthe PES packet appears first) contains an access point of the videostream or the audio stream. Particularly, for the video stream, thisindicates that the I-picture is included.

This random access indicator can be used for determining the videoobject unit, and creating the T map.

The transport packet has a fixed size of 188 bytes. Therefore, aplurality of transport packets (2048 bytes/188 bytes=10 TS packets) arerecorded in one sector of the DVD-RAM comprising 2048 bytes. While it ispossible to handle as 1 pack=1 sector in the movie object (M_VOB), it isimpossible in the digital broadcasting object (D_VOB). Datareading/writing in the DVD-RAM can only be made by the sector. Thereforeeven in the digital broadcasting object, information in the T map ismade up of the playback time length of the movie object unit (VOBU)expressed by the number of video fields, and the data size of the movieobject unit expressed by the number of sectors.

For the above reason, accuracy of the address is not secured in the Tmap when the movie object unit is defined to be from a transport packetto the next transport packet. Therefore, the movie object unit (VOBU) isdefined by using the sector containing the transport packet.

A PROVIDER_INF field of the digital broadcasting object streaminformation (D_VOB_STI) includes an ID for identifying a broadcastingcompany and particular information related to each broadcasting company.

Referring now to FIG. 15, description will be made for the audio objectinformation (AOBI). Again, as a subclass derived from the objectinformation, the audio object information is basically the same as inthe case of the movie object information. A big difference, however, isthat the audio object is an object for the audio system only and is notformatted into the MPEG system stream. More details will be describedhere below.

Since the audio object is not formatted into the MPEG system stream, notime stamps are included in the audio object. Therefore, there is noreference time for indicating the playback start time or the playbackend time of the cell or the object. Thus, the audio object start time(AOB_A_S_TM) in the audio object general information (AOBI_GI) isentered with 0, whereas the audio object end time (AOB_A_E_TM) isentered with the playback time length. Further, each of the Start fieldand the End field in the cell information is entered with relative timewithin the audio object.

Another difference of the audio data from the MPEG video data is thatplayback of the audio data can be started at any audio frame unit.Therefore, the audio object unit (AOBU) can be defined as the audioframe multiplied by any integer. If the audio object unit is too small,however, a huge amount of data must be handled in the T map. So, theaudio object unit is made to be almost the same length as the objectunit of the movie object, which is about 0.5 second. The T map managesthe playback time length and the data size for each audio object unit.

Referring now to FIG. 16, description will be made for the still pictureobject information (S_VOBSI). Again, as a subclass derived from theobject information, the still picture object information (S_VOBSI) isbasically the same as in the case of the movie object information. A bigdifference, however, is that the still picture object is an objectincluding data of a plurality of still pictures, and that the stillpicture object is not formatted into the MPEG system stream. Moredetails will be described for the audio object information here below.

The still picture, differing from the movie or the sound, does not havetime information. Thus, fields of the starting information and theending information in the still picture object general information(S_VOBS_GI) are entered with a number representing the starting stillpicture (Start_Video) and a number representing the last still picture(End_Video) respectively. Further, the Start field and the End field inthe cell are entered with respective picture numbers within the stillpicture object instead of the time information.

The smallest access unit in still pictures is the frame of stillpicture. Thus, the S map is defined as the access map, which is a tablecontaining the data size (S_VOB_SZ) of each still picture.

The overall data structure described so far above is shown in FIG. 17.FIG. 17 shows the entirety of the management information in the DVD-RAM.With reference to FIG. 17, all of the management information will bedescribed here below. As shown in FIG. 17, the DVD-RAM according to thepresent embodiment is provided with video manager general information(VMGI) 90 and a variety of information tables 92, 94, 96 and 98 inaddition to the PGC information 50 and 70.

The VMGI 90 is management information for the whole disc, which containspointer information, i.e. start addresses, of the original PGCinformation 50, the user-defined PGC information 70, and the variety offile management tables 92, 94, . . . Access to these tables 50, 70, 92,94, . . . becomes possible by referring to the pointer information.

Now, the file management tables 92, 94, 96 and 98 shown in FIG. 17 willbe detailed here. Each of these tables 92, 94, 96, 98 is a table formanaging data files comprising the objects, and is prepared for eachkind of objects. For example, the table 92 is for managing the moviefiles containing movie objects, whereas the table 94 is for managing thestill picture files containing still picture objects.

As described above, the object information is identified based on theobject ID stored in the cell information in the PGC information. Duringthis operation address of the object information is identified via thefile management table 92, 94, 96 or 98. For this purpose, each of thefile management tables 92, 94, 96, 98 contains information about thenumber of objects under management, ID's of the objects, the size ofeach object information, and so on. For example, when the object IDshows a sequent order, based on this object ID specified by the cellinformation, it is possible to determine an order of the objectspecified by the cell information in the, object information managed bythe file management table. Then, from the order of this determinedobject information and the file size, an offset based on the startaddress of the file management table can be calculated to obtain logicaladdress of this determined object information.

As shown in FIG. 17, the movie file management table 92 is a table formanaging movie files containing movie objects. The movie file managementtable 92 includes the movie object information (M_VOBI) 92 a, 92 b, . .. , and the table managing information (M_AVFITI) 92 h containing thenumber of movie object information and the size of the movie objectsmanaged by the table 92. The disc successively records same number ofmovie object information as the number of movie object informationcontained in the information 92 h. As mentioned earlier, the movieobject information 92 a, . . . each includes the general information(M_VOB_GI), stream information (M_VOB_STI), and the T map. Further, theT map includes the display time and size (VOBU_ENT) for each object unit(VOBU).

The same structure is used in a table (S_AVFIT) 94 for managing stillpicture files containing still picture objects, a table (D_AVFIT) 96 formanaging digital broadcasting files containing digital broadcastingobjects, and a table (A_AVFIT) 98 for managing audio files containingaudio objects.

The original PGC information 50 contains the cell information 61, 62,63, . . . , in the order of playback. The cell information containsinformation corresponding to the object information (type and object ID)and the playback section information (Start and End) within the object.The playback section information shown in the cell can be converted toaddress information of the object substance through the access map inthe object information.

As described earlier, the original PGC information 50 differs from theuser-defined PGC information 70 only in that the original PGCinformation 50 is automatically generated by the recorder so that all ofthe objects recorded in the disc will be played whereas the user-definedPGC information 70 is information in which the user can freely definethe playback sequence. Thus, the user-defined PGC information 70 has thesame structure with the original PGC information 50.

By abstracting in advance the information for managing the AV streams,it becomes possible to define the playback control information such asthe PGC information and cell information without depending on theinformation peculiar to a given AV stream format, making possible tointegrally manage AV streams. Thus, environment can be realized in whichusers can play AV data without paying attention to the AV format.

Further by using the above-described data structure, a new AV format canbe easily incorporated into the data structure in DVD-RAM by simplydefining the management information derived from the object informationin the same manner as the other existing AV formats.

(Player Model)

Referring now to FIG. 18, a player model for playing the above opticaldisc is described. As shown in FIG. 18, the player comprises a pickup1701, an ECC processor 1702, a track buffer 1703, a PS decoder 1705, aTS decoder 1706, an audio decoder 1707, a still picture decoder 1708, aswitch 1710 and a controller 1711. The optical pickup 1701 reads outdata from the optical disc 100. The ECC processor 1702 performs errorcorrection and other operations to the read data. The track buffer 1703tentatively stores the data after the error correction. The PS decoder1705 decodes to play program streams such as the movie object (M_VOB).The TS decoder 1706 decodes to play transport streams such as thedigital broadcast object (D_VOB). The audio decoder 1707 decodes to playthe audio object (AOB). The still picture decoder 1708 decodes to playthe still picture object. The switch 1708 switches among the decoders1705, 1706, . . . , for entry of data. The controller 1711 controls eachcomponent of the player.

The data recorded on the optical disc 100 is read by the pickup 1701 ,goes through the ECC processor 1702, and is stored in the track buffer1703. The data stored in the track buffer 1703 is then entered into oneof the decoders 1705, 1706, 1707 and 1708, and then decoded to beoutputted therefrom. In this switching operation, the controller 1711checks the read data and sees the type information of the cellinformation in the PGC information providing the playback sequenceaccording to the method described earlier. The switch 1710 is controlledto switch according to the type information so that the read informationis sent to an appropriate decoder. information of the cell informationin the PGC information providing the playback sequence according to themethod described earlier. The switch 1710 is controlled to switchaccording to the type information so that the read information is sentto an appropriate decoder.

The player of the present embodiment further comprises a digitalinterface 1704 for supplying the AV stream to external equipment.Through this interface with an appropriate communication protocol suchas IEEE1394 and IEC958, the AV stream can be fed to the externalequipment. This is especially advantageous when a program of a new AVformat is outputted through the digital interface 1704 to be played inthe external AV equipment, without using the decoders in this player.

On the other hand, to support a new AV format in this player, a newdecoder 1709 adapting to the new AV format may be coupled to the trackbuffer 1703 in the same way as the other existing decoders 1705-1708.

(Recording Operation by DVD Recorder)

Next, reference is made to FIG. 19 to describe the structure andoperation of a DVD recorder according to the present invention forplaying (reproducing)/recording the above optical disc.

As shown in the figure, the DVD recorder comprises a user interface1901, a system controller 1902, an analog tuner 1903, an encoder 1904, adigital tuner 1905, an analyzer 1906, a display apparatus 1907, and adecoder 1908. The user interface 1901 provides a display for the userand receives requests from the user. The system controller 1902 managesand overall controls the DVD recorder. The analog tuner 1903 receivesVHF and UHF waves. The encoder 1904 converts analog signals into digitalsignals to encode the digital signal into an MPEG program stream. Thedigital tuner 1905 receives satellite digital broadcasting. The analyzer1906 analyzes an MPEG transport stream sent from the digital broadcastsatellite. The display apparatus 1907 includes a TV monitor and speakersystem. The decoder 1908 decodes the AV streams. The decoder 1908includes decoders shown in FIG. 18. The DVD recorder further comprises adigital interface 1909, a track buffer 1910 for temporary storage of thedata to be written, and a drive 1911 for writing data on the DVD-RAM100. The digital interface 1909 is an interface for outputting toexternal equipment through such a protocol as IEEE1394.

In the DVD recorder having the above configuration, the user interfaceportion 1901 first receives demand from the user. The user interface1901 transmits a request from the user to the system controller 1902.The system controller 1902 interprets the request into commands to sendto appropriate modules. When the request from the user is to record ananalog broadcasting program, the system controller 1902 requests thetuner 1903 to receive the program, and the encoder 1904 to encode.

The encoder 1904 performs video encoding, audio encoding and systemencoding on the AV data received from the analog tuner 1903 to outputthe encoded data to the track buffer 1910.

The encoder 1904, upon commencing the encoding operation, sends theplayback start time (M_VOB_V_S_PTM) of the MPEG program stream encodedto the system controller 1902, and then in parallel with the encodingoperation, sends the time length and size information of the movieobject unit (VOBU) to the system controller 1902 as source informationfor creating the T map.

Next, the system controller 1902 issues a recording request to the drive1911, so that the drive 1911 takes data stored in the track buffer 1910and records this information on the DVD-RAM disc 100. At that time, thesystem controller 1902 instructs the drive 1911 where to store theinformation on the disc 100 according to the allocation information ofthe file system.

Ending of the recording operation is demanded by the user through a stoprequest. The stop request from the user is transmitted through the userinterface 1901 to the system controller 1902. The system controller 1902then issues the stop request to the analog tuner 1903 and the encoder1904.

Upon reception of the stop request from the system controller 1902, theencoder stops the encoding operation, and sends the playback stop time(M_VOB_V_E_PTM) of the last encoded MPEG program stream to the systemcontroller 1902.

After the encoding operation is over, the system controller 1902 createsthe movie object information (M_VOBI) based on the information receivedfrom the encoder 1904. Next, the system controller 1902 creates the cellinformation corresponding to the movie object information (M_VOBI). Theimportant point here is that the type information in the cellinformation must be specified as “M_VOB”. As described earlier, theinformation in the cell information is configured without depending onthe movie object (M_VOB), and all information which depends on the movieobject (M_VOB) is concealed into the movie object information (M_VOBI).Therefore, an error in recognizing the type information in the cellinformation will lead to inability to perform normal playback, possiblyresulting in system shut down.

Finally, the system controller 1902 requests the drive 1911 to finishrecording the data stored in the track buffer 1910, and to record themovie object information (M_VOBI) and cell information. The drive 1911records the data remaining in the track buffer 1910, the movie objectinformation (M_VOBI) and the cell information on the DVD-RAM,subsequently completing the recording operation.

Next, description will be made in a case of the user's request forrecording a digital broadcast program.

The user's request for recording the digital broadcasting program istransmitted through the user interface 1901 to the system controller1902. The system controller 1902 then requests the digital tuner 1905 torecord, and the analyzer 1906 to analyze received data.

An MPEG transport stream sent from the digital tuner 1905 is sentthrough the analyzer 1906 to the track buffer 1910. The analyzer 1906first picks up from the MPEG transport stream the start time information(D_VOB_V_S_PTM) as information necessary for generating the digitalbroadcasting object information (D_VOBI), and sends this information tothe system controller 1902. Next, the analyzer 1906 determines the movieobject unit (VOBU) in the MPEG transport stream, and sends the timelength and size of the movie object unit as information necessary forcreating the T map to the system controller 1902. It should be notedthat the movie object unit (VOBU) can be determined, as describedearlier, based on the random access indicator (random_access_indicator)in the application field contained in the TS packet header.

Next, the system controller 1902 outputs a recording request to thedrive 1911. Then the drive 1911 picks up the data stored in the trackbuffer 1910 and records the data in the DVD-RAM disc 100. At this time,the system controller 1902 also informs the drive 1911 where the drive1911 should record the information on the disc 100, based on allocationinformation of the file system.

Ending of the recording operation is instructed by the user through astop request. The stop request from the user is transmitted through theuser interface 1901 to the system controller 1902. The system controller1902 then issues the stop request to the digital tuner 1905 and theanalyzer 1906.

The analyzer 1906, upon reception of the stop request from the systemcontroller 1902, stops the analyzing operation, and sends the displayend time (D_VOB_V_E_PTM) of the movie object unit (VOBU) of the lastanalyzed MPEG transport stream to the system controller 1902.

After the completion of receiving the digital broadcasting, the systemcontroller 1902 creates the digital broadcasting object information(D_VOBI) based on the information received from the analyzer 1906, andnext, creates the cell information corresponding to the digitalbroadcasting object information (D_VOBI), at which time the typeinformation in the cell information is specified as “D_VOB”.

Finally, the system controller 1902 requests the drive 1911 to finishrecording the data stored in the track buffer 1910, and to record thedigital broadcasting object information and cell information. The drive1911 records the data remaining in the track buffer 1910, the digitalbroadcasting object information (D_VOBI) and the cell information on theDVD-RAM disc 100, completing the recording operation.

The above description is made on the basis that the user makes requestto start and stop recording. When a timer recording function commonlyprovided in a VTR system is used, the system controller automaticallyissues recording start and stop commands instead of the commands beingissued by the user's request, and thus the steps of operation performedby the DVD recorder are essentially the same.

(Playback Operation by DVD Recorder)

Next, playback operation in the DVD recorder will be described.

First, the user interface 1901 receives a request from the user. Theuser interface 1901 transmits the request to the system controller 1902.The system controller 1902 interprets the user's request to commands tosend them to appropriate modules. For example, when the user's requestdemands playback of a PGC information, the system controller 1902analyzes the PGC information and cell information to see which objectshould be played. Description will be made below for a case in which anoriginal PGC comprising one movie object (M_VOB) and one cellinformation is played.

The system controller 1902 first analyzes the type information stored inthe cell information in the PGC information. When the type informationis “M_VOB”, it means that the AV stream to be played is the streamrecorded as the MPEG program stream. Next, the system controller 1902refers to the ID of the cell information to find the corresponding movieobject information (M_VOBI) from the table (M_AVFIT). The systemcontroller 1902 then finds start address and end address of the AV datato be played according to the start time information (M_VOB_V_S_PTM) andend time information (M_VOB_V_E_PTM) contained in the movie objectinformation, and T map.

Next, the system controller 1902 sends to the drive 1911 a request forreading from DVD-RAM 100, together with the start address of thereading. The drive 1911 then reads out AV data from the address given bythe system controller 1902, and stores the read data to the track buffer1910.

Next, the system controller 1902 sends to the decoder 1908 a decodingrequest of the MPEG program stream. The decoder 1908 then read out theAV data stored in the track buffer 1910 to decode the read data. Thedecoded AV data is outputted through the display apparatus 1907.

On the completion of reading all the data instructed by the systemcontroller 1902, the drive 1911 reports to the system controller 1902that the reading operation is completed. The system controller 1902 thenissues a command to the decoder 1908 to stop the playback operation. Thedecoder 1908 continues to decode data until the track buffer 1910 isemptied. After all the data is decoded and played, the decoder 1908reports to the system controller 1902 that the replay operation isfinished, then bringing the playback operation to a complete end.

The above description was made for the case in which one original PGCcontaining one movie object (M_VOB) and one cell information is to beplayed. However, the playback operation of the AV stream can beperformed by the same steps of operation whether the original PGCcontains only one digital broadcasting object (D_VOB), contains aplurality of movie objects, contains a plurality of digital broadcastingobjects, or contains both movie objects and digital broadcasting object.Further, the same goes with a case in which the original PGC contains aplurality of cells, or in a case of the user-defined PGC.

Further, the audio object (AOB) and other AV stream, i.e. the stillpicture object (S_VOBS) are handled essentially in the same proceduresby the same modules, differing only in the configuration within thedecoder 1908. In these cases, the decoder 1908 may be configured by thePS decoder 1705, the TS decoder 1706, the audio decoder 1707, or thestill picture decoder 1708 as shown in FIG. 18.

Next, an example is taken for a case in which the decoder 1908 does nothave capabilities for playing all kinds of the AV streams.

If the decoder 1908 does not have playback capability for the MPEGtransport stream, playback operation by the decoder 1908 is impossibleas described above. In such a case the digital interface portion 1909 isused to supply external equipment with the data, so that the data can beplayed by the external equipment.

When the system controller 1902 finds from the cell information in thePGC information that the user requests playback of a digitalbroadcasting object (D_VOB) not supported by the system, the systemcontroller 1902 requests the digital interface 1909 for external outputinstead of requesting the decoder 1908 for playback. The digitalinterface 1909 transmits AV data stored in the track buffer 1910 inaccordance with the communication protocol of the connected digitalinterface. Other operations performed are the same as those performedwhen the movie object (M_VOB) is played.

A judgment must be made whether or not the decoder 1908 is compatiblewith the AV stream requested for replay. This judgment may be made bythe system controller 1902 by itself, or the system controller 1902 mayask the decoder 1908.

(DVD Player)

Next, with reference to FIG. 20, a DVD player according to the presentinvention is described. The DVD player is a realization of the playermodel described above to play the above optical disc.

As shown in the figure, the DVD player comprises a user interface 2001,a system controller 2002, a display apparatus 2003, a decoder 2004, adigital interface 2005, a track buffer 2006 and a drive 2007. The userinterface 2001 receives requests from the user and displays someindications to the user. The system controller 2002 manages and controlsoverall of the DVD player. The display apparatus 2003 includes a TVmonitor and speaker system. The decoder 2004 decodes the MPEG stream.The digital interface 2005 connects to IEEE1394 and so on. The trackbuffer 2006 temporally stores the data read from the DVD-RAM 100. Thedrive 2007 reads data out from the DVD-RAM 100. The DVD playerconfigured as above performs the same playback operations as in the DVDrecorder described earlier.

It should be noted that the DVD-RAM is taken as an example in thepresent embodiment. However, the same description so far has been madeapplies to other media. The present invention should not be limited tosuch media as the DVD-RAM and other optical discs.

Further, according to the present embodiment, the AV stream notsupported by the decoder is played through the digital interface.However, those AV streams which are supported by the decoder may beoutputted to external equipment through the digital interface dependingon the request from the user.

Further, according to the present embodiment, the audio data and thestill picture data were treated as unique data differing from the MPEGstreams. However, these data may also be recorded in the format of MPEGsystem stream.

Although the present invention has been described in connection withspecified embodiments thereof, many other modifications, corrections andapplications are apparent to those skilled in the art. Therefore, thepresent invention is not limited by the disclosure provided herein butlimited only to the scope of the appended claims.

What is claimed is:
 1. An information recording medium for recording atleast one object and management information for managing the recordedobject, each object comprising a plurality of object units each havingan address indicative of a location on the medium, the managementinformation including program chain information and object information,wherein the program chain information includes a sequence of cellinformation, each cell information indicating a playback section of oneof the at least one object as a cell and including playback sectioninformation indicating start and end portions of a part or whole of theassociated object, and wherein the object information is provided foreach recorded object, and wherein the medium is provided for recordingtwo or more types of objects including a type indicative of a movieobject and a type indicative of a still picture object, the cellinformation further includes type information indicating a type of theobject with which the cell is associated, the object informationincludes a plurality of kinds of information in a form depending on thetype of the associated object, the plurality of kinds of informationincluding map information for obtaining an address of each object unit,and the object information associated with the movie object includesstarting time information and ending time information respectivelyindicating a starting time and an ending time of the associated movieobject, while the object information associated with the still pictureobject includes an ending picture number representing the number of anending still picture of the associated still picture object.
 2. A methodfor recording at least one object on an information medium, comprising:recording the at least one object wherein each object includes aplurality of object units each having an address indicative of alocation on the medium; and recording management information formanaging the recorded object on the medium to include object informationfor each of the at least one object and program chain informationincluding a sequence of cell information, each cell informationindicating a playback section of one of the at least one object as acell and including playback section information indicating start and endportions of a part or whole of the associated object, wherein the mediumis provided for recording two or more types of objects including a typeindicative of a movie object and a type indicative of a still pictureobject, the cell information further including type informationindicating a type of the object with which the cell is associated, theobject information includes a plurality of kinds of information in aform depending on the type of the associated object, the plurality ofkinds of information including map information for obtaining an addressof each object unit, and the object information associated with themovie object includes starting time information and ending timeinformation respectively indicating a starting time and an ending timeof the associated movie object, while the object information associatedwith the still picture object includes an ending picture numberrepresenting the number of an ending still picture of the associatedstill picture object.
 3. The method of claim 2, wherein it is determineddepending on the type of the object which kind of information isincluded in the object information.
 4. The method of claim 2, whereinthe number of the kinds of information included in the objectinformation changes depending on the type of the associated object. 5.The method of claim 2, wherein the number of the kinds of informationincluded in the object information associated with the movie object isdifferent from that associated with the still picture object.
 6. Themethod of claim 2, wherein the cell information associated with themovie object includes, as the section information, starting timeinformation and ending time information respectively indicating astarting time and an ending time of the associated movie object, whilethe cell information associated with the still picture object includes,as the section information, a starting picture number and an endingpicture number respectively representing the number of a starting stillpicture and the number of an ending still picture of the associatedstill picture object.
 7. A reproducing apparatus for reproducing atleast one object stored on an information medium, each object comprisinga plurality of object units each having an address indicative of alocation on the information medium, the apparatus comprising: a driveoperable to read the at least one object and management information formanaging reproduction of the at least one object from the informationmedium; a decoder operable to decode the read at least one object toobtain data to be presented; and a controller operable to control thedrive and the decoder, wherein the management information includesobject information provided for each object and program chaininformation that includes a sequence of cell information, each cellinformation indicating a playback section of one of the at least oneobject as a cell and including playback section information indicatingstart and end portions of a part or whole of the associated object,wherein the medium is provided for recording two or more types ofobjects including a type indicative of a movie object and a typeindicative of a still picture object, the cell information furtherincludes type information indicating a type of the object of theassociated cell, the object information includes a plurality of kinds ofinformation in a form depending on the type of the corresponding object,the plurality of kinds of information including map information forobtaining an address of each object unit, the object informationassociated with the movie object including starting time information andending time information respectively indicating a starting time and anending time of the associated movie object, while the object informationassociated with the still picture object including an ending picturenumber representing the number of an ending still picture of theassociated still picture object, and wherein the controller retrieves atleast one of the plurality of kinds of information included in theobject information based on the type of the object corresponding to eachof the cells defined by the sequence of cell information to bereproduced, and controls the drive to read a part or the whole of the atleast one object in accordance with the sequence of cell information tobe reproduced by using the retrieved information.
 8. The reproducingapparatus of claim 7, wherein it is determined depending on the type ofthe object which kind of information is included in the objectinformation.
 9. The reproducing apparatus of claim 7, wherein the numberof the kinds of information included in the object information changesdepending on the type of the associated object.
 10. The reproducingapparatus of any one of claim 7, wherein the number of the kinds ofinformation included in the object information associated with the movieobject is different from that associated with the still picture object.11. The reproducing apparatus of any one of claim 7, wherein the cellinformation associated with the movie object includes, as the sectioninformation, starting time information and ending time informationrespectively indicating a starting time and an ending time of theassociated movie object, while the cell information associated with thestill picture object includes, as the section information, a startingpicture number and an ending picture number respectively representingthe number of a starting still picture and the number of an ending stillpicture of the associated still picture object.
 12. A recordingapparatus for recording at least one object on an information medium,comprising: a unit for recording the at least one object wherein eachobject includes a plurality of object units each having an addressindicative of a location on the medium; and a unit for recordingmanagement information for managing the recorded object on the medium toinclude object information for each of the at least one object andprogram chain information including a sequence of cell information, eachcell information indicating a playback section of one of the at leastone object as a cell and including playback section informationindicating start and end portions of a part or whole of the associatedobject, wherein the medium is provided for recording two or more typesof objects including a type indicative of a movie object and a typeindicative of a still picture object, the cell information furtherincluding type information indicating a type of the object with whichthe cell is associated, the object information includes a plurality ofkinds of information in a form depending on the type of the associatedobject, the plurality of kinds of information including map informationfor obtaining an address of each object unit, and the object informationassociated with the movie object includes starting time information andending time information respectively indicating a starting time and anending time of the associated movie object, while the object informationassociated with the still picture object includes an ending picturenumber representing the number of an ending still picture of theassociated still picture object.
 13. The recording apparatus of claim12, wherein it is determined depending on the type of the object whichkind of information is included in the object information.
 14. Therecording apparatus of claim 12, wherein the number of the kinds ofinformation included in the object information changes depending on thetype of the associated object.
 15. The recording apparatus of claim 12,wherein the number of the kinds of information included in the objectinformation associated with the movie object is different from thatassociated with the still picture object.
 16. The recording apparatus ofclaim 12, wherein the cell information associated with the movie objectincludes, as the section information, starting time information andending time information respectively indicating a starting time and anending time of the associated movie object, while the cell informationassociated with the still picture object includes, as the sectioninformation, a starting picture number and an ending picture numberrespectively representing the number of a starting still picture and thenumber of an ending still picture of the associated still pictureobject.